HISTOLOGIC AND MORPHOMETRIC GRADING OF GLIOMAS : A COMPARATIVE SURVIVAL ANALYSIS

OBJECTIVE: A grading system based upon morphometrically assessed quantitative parameters (HOM system) was correlated with the results of classical histologic grading (St. Anne/Mayo system [SAMS], 1988, and World Health Organization classification, 1993). Validation was done by comparison with survival data. STUDY DESIGN: This retrospective study consisted of representative paraffin-embedded tissue sections of 139 adults who had been surgically treated for supratentorial common gliomas between 1988 and 1994. Histologic grading diagnoses were adapted to the latest standard. Computer-assisted image analysis of Ki-67 (MIB1)/ Feulgen-stained sections provided nuclear parameters appropriate to define homogeneous grades of malignancy by multivariate statistical analyses: average segment length of the minimum spanning trees (ASLMST) for the quantitation of tumor growth pattern; nuclear area percentage (NAP), reflecting cellularity; and volume-weighted mean nuclear volumes (vV) for estimating nuclear size and pleomorphism. RESULTS: Analysis of survival data yielded no statistically significant differences between astrocytomas and oligoastroacytomas (Lee-Desu test, alpha = 5%). Furthermore, only two prognostically different grades could be established, "low grade" and "high grade" gliomas, with the first representing SAMS grades 2 and 3 and the latter SAMS grade 4 (alpha = .1%). The same applied to HOM grades (alpha = .1%). Cox regression analysis of survival data demonstrated that histologic grading diagnoses and NAP tallied best with patients' outcome.